Air filter



FIG. 1 is a first perspective view of the air filter embodying our new design;

FIG. 2 is a second perspective view the air filter of FIG. 1;

FIG. 3 is a top view the air filter of FIG. 1;

FIG. 4 is a bottom view the air filter of FIG. 1;

FIG. 5 is a first side view the air filter of FIG. 1;

FIG. 6 is a second side view the air filter of FIG. 1; and,

FIG. 7 is a third side view the air filter of FIG. 1.

Although not shown, a fourth side view of the air filter of FIG. 1 is identical to the third side view shown in FIG. 7 and corresponds to an opposite side of the air filter in FIG. 7. In the drawings, the broken lines show portions of the air filter that form no part of the claimed design. 

CLAIM The ornamental design for an air filter, as shown and described. 